The present invention relates to rotary motion V-ball-type control valves.
Rotary motion V-ball-type control valves are commonly employed in applications where it is necessary to maintain efficient control over operational flows ranging from very low to very high. In this regard, V-ball-type control valves provide a high degree of rangeability. Rangeability is defined as the ratio between the maximum and minimum controllable flow rates provided by the valve. The rangeability of a rotary motion V-ball control valve will typically be in the neighborhood of about 300:1. In contrast, the rangeability of a linear motion plug-type control valve will typically be in the neighborhood of only about 50:1.
A rotary motion V-ball control valve of the type heretofore known in the art will commonly comprise: a valve body having flanges or other suitable structures provided at the inlet and outlet ends thereof for installing the valve body in a piping system; a V-type valve ball element rotatably positioned in the valve body; and an operating shaft secured to the V-ball element and rotatably extending laterally through the wall (typically the side wall) of the valve body. The control valve can be employed to automatically regulate fluid flow rates, regulate fluid pressures, maintain vessel liquid levels, or control other flow-related operations. The control valve is typically operated by connecting a rotary motion actuator to the exterior end of the operating shaft. Such rotary motion actuators are commonly either pneumatically or electrically operated.
The name xe2x80x9cV-ballxe2x80x9d refers to a V-shaped contour provided in the leading edge of the rotatable valve ball element. This feature contributes greatly to the ability of the valve to provide effective control even at very low flow rates (i.e., when the valve is very near its closed position).
Unfortunately, rotary motion V-ball-type control valves have heretofore had one significant shortcoming. In contrast to most top entry, linear motion plug-type valves, the interior components of V-ball. control valves have not been accessible for inspection, maintenance, or replacement without removing the valve body from the piping system. Thus, although initially less expensive than linear motion valves to purchase, V-ball control valves can be more difficult and costly to maintain and repair.
The present invention provides an improved rotary motion V-ball-type control valve which satisfies the needs and alleviates the problems discussed hereinabove. The inventive valve includes: a valve body installable in a piping system; a V-ball-type valve element rotatably positioned in the valve body; and a valve shaft extending from the valve ball element. The improvement of the present invention comprises a bonnet removably attached to the valve body such that the valve shaft is rotatably positioned through the bonnet. The improvement further comprises the bonnet, the valve shaft, and the valve ball element all being removable from the valve body while the valve body is installed in the piping system.
Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.